1. Field of the Invention
The present invention relates to optical gyroscopes and more particularly to passive ring resonator gyroscopes which have bias and frequency errors resulting from mechanically or thermally induced dimensional changes
2. Description of Related Applications and Patents
This application reltates to seven previously submitted applications:
Ser. No. 676,322, "PASSIVE RING RESONATOR GYROSCOPE", filed Nov. 29, 1984, inventor Sanders et al; PA1 Ser. No. 701,891, "TWO SERVO LOOP PASSIVE RING LASER GYROSCOPE", filed Feb. 13, 1985, inventors SooHoo and Valle; PA1 Ser. No. 839,292, "TWO SOURCE LASER PASSIVE RING LASER GYROSCOPE", filed Mar. 13, 1986, inventor SooHoo; issued Feb. 28, 1989, U.S. Pat. No. 4,807,999; PA1 Ser. No. 864,232, "PHASE LOCKED PASSIVE RING LASER GYROSCOPE", filed May 19, 1986, inventor SooHoo; issue Mar. 28, 1989, U.S. Pat. No. 4,815, 851; PA1 Ser. No. 028,033, "IDENTICAL SERVO FREQUENCY MODULATED PASSIVE RING LASER GYROSCOPE", filed Mar. 23, 1987, inventor SooHoo; PA1 Ser. No. 044,921, "BALANCED DUAL SERVO VCO PASSIVE RING LASER GYROSCOPE", filed May 01, 1987, inventor SooHoo; issued May 16, 1989, U.S. Pat. No. 4,830,495; PA1 Ser. No. 077,134, "BALANCED DUAL SERVO FREQUENCY MODULATED VCO PASSIVE RING LASER GYROSCOPE", filed Jul. 23, 1987, inventors SooHoo and Doty.
This application was abnadoned sunsequent to filing this application.
Each of the above related applications have a common assignee.
All seven of these applications, describe a laser gyro having a single piece body incorporating a linear laser light source and a passive resonant cavity.
This first applicaiton, Ser. No. 676,322, relies on three active servo loops for operation.
The second previous application, Ser, No. 701,891, describes a gyroscope having a single linear laser light source and a passive resonant cavity. This seond gyro uses a first and second active servo loop for operation.
The third application, Ser. No. 839,292 describes a gyroscope having two laser sources. A first laser source produces a clockwise beam and a second laser source to produces a counterclockwise beam. Both beans circulating in a sealed, evacuated passive cavity within the same body.
The fourth application, Ser. No. 864,232 describes a gyroscope using an external modulator to frequency modulate the input source beam and subsequently the detected clockwise and counterclockwise beams are demodulated at this same frequency to produce a more sensitive phase detection scheme.
The fifth application, Ser. No. 028,033, describes a gyroscope using an external modulator to frequency modulate the input beam and the output beams are phase demodulated at this same frequency. In this application, two identical servo loops plus a cavity sum servo are used to create a more symmetric and sensitive servo system.
The sixth application, Ser. No. 044,921, describes a gyroscope having two identical balanced servo loops plus a cavity servo based on a PZT dither on the passive cavity.
The parent application, Ser. No. 077,134 describes a gyroscope with different frequency modulations applied to the two acousto-optic modulators. In this application two identical servo loops plus a cavity sum servo are used to create a symmetric servo system.